export default function(coder: any) {

  coder['math_number'] = function(block: any) {
    // Numeric value.
    var code = parseFloat(block.getFieldValue('NUM'));
    var order = code >= 0 ? coder.ORDER_ATOMIC :
                coder.ORDER_UNARY_NEGATION;
    return [code, order];
  };

  coder['math_arithmetic'] = function(block: any) {
    // Basic arithmetic operators, and power.
    var OPERATORS: any = {
      'ADD': [' + ', coder.ORDER_ADDITION],
      'MINUS': [' - ', coder.ORDER_SUBTRACTION],
      'MULTIPLY': [' * ', coder.ORDER_MULTIPLICATION],
      'DIVIDE': [' / ', coder.ORDER_DIVISION],
      'POWER': [null, coder.ORDER_COMMA]  // Handle power separately.
    };
    var tuple = OPERATORS[block.getFieldValue('OP')];
    var operator = tuple[0];
    var order = tuple[1];
    var argument0 = coder.valueToCode(block, 'A', order) || '0';
    var argument1 = coder.valueToCode(block, 'B', order) || '0';
    var code;
    // Power in JavaScript requires a special case since it has no operator.
    if (!operator) {
      code = 'Math.pow(' + argument0 + ', ' + argument1 + ')';
      return [code, coder.ORDER_FUNCTION_CALL];
    }
    code = argument0 + operator + argument1;
    return [code, order];
  };

  coder['math_single'] = function(block: any) {
    // Math operators with single operand.
    var operator = block.getFieldValue('OP');
    var code;
    var arg;
    if (operator == 'NEG') {
      // Negation is a special case given its different operator precedence.
      arg = coder.valueToCode(block, 'NUM',
          coder.ORDER_UNARY_NEGATION) || '0';
      if (arg[0] == '-') {
        // --3 is not legal in JS.
        arg = ' ' + arg;
      }
      code = '-' + arg;
      return [code, coder.ORDER_UNARY_NEGATION];
    }
    if (operator == 'SIN' || operator == 'COS' || operator == 'TAN') {
      arg = coder.valueToCode(block, 'NUM',
          coder.ORDER_DIVISION) || '0';
    } else {
      arg = coder.valueToCode(block, 'NUM',
          coder.ORDER_NONE) || '0';
    }
    // First, handle cases which generate values that don't need parentheses
    // wrapping the code.
    switch (operator) {
      case 'ABS':
        code = 'Math.abs(' + arg + ')';
        break;
      case 'ROOT':
        code = 'Math.sqrt(' + arg + ')';
        break;
      case 'LN':
        code = 'Math.log(' + arg + ')';
        break;
      case 'EXP':
        code = 'Math.exp(' + arg + ')';
        break;
      case 'POW10':
        code = 'Math.pow(10,' + arg + ')';
        break;
      case 'ROUND':
        code = 'Math.round(' + arg + ')';
        break;
      case 'ROUNDUP':
        code = 'Math.ceil(' + arg + ')';
        break;
      case 'ROUNDDOWN':
        code = 'Math.floor(' + arg + ')';
        break;
      case 'SIN':
        code = 'Math.sin(' + arg + ' / 180 * Math.PI)';
        break;
      case 'COS':
        code = 'Math.cos(' + arg + ' / 180 * Math.PI)';
        break;
      case 'TAN':
        code = 'Math.tan(' + arg + ' / 180 * Math.PI)';
        break;
    }
    if (code) {
      return [code, coder.ORDER_FUNCTION_CALL];
    }
    // Second, handle cases which generate values that may need parentheses
    // wrapping the code.
    switch (operator) {
      case 'LOG10':
        code = 'Math.log(' + arg + ') / Math.log(10)';
        break;
      case 'ASIN':
        code = 'Math.asin(' + arg + ') / Math.PI * 180';
        break;
      case 'ACOS':
        code = 'Math.acos(' + arg + ') / Math.PI * 180';
        break;
      case 'ATAN':
        code = 'Math.atan(' + arg + ') / Math.PI * 180';
        break;
      default:
        throw Error('Unknown math operator: ' + operator);
    }
    return [code, coder.ORDER_DIVISION];
  };

  coder['math_constant'] = function(block: any) {
    // Constants: PI, E, the Golden Ratio, sqrt(2), 1/sqrt(2), INFINITY.
    var CONSTANTS: any = {
      'PI': ['Math.PI', coder.ORDER_MEMBER],
      'E': ['Math.E', coder.ORDER_MEMBER],
      'GOLDEN_RATIO':
          ['(1 + Math.sqrt(5)) / 2', coder.ORDER_DIVISION],
      'SQRT2': ['Math.SQRT2', coder.ORDER_MEMBER],
      'SQRT1_2': ['Math.SQRT1_2', coder.ORDER_MEMBER],
      'INFINITY': ['Infinity', coder.ORDER_ATOMIC]
    };
    return CONSTANTS[block.getFieldValue('CONSTANT')];
  };

  coder['math_number_property'] = function(block: any) {
    // Check if a number is even, odd, prime, whole, positive, or negative
    // or if it is divisible by certain number. Returns true or false.
    var number_to_check = coder.valueToCode(block, 'NUMBER_TO_CHECK',
        coder.ORDER_MODULUS) || '0';
    var dropdown_property = block.getFieldValue('PROPERTY');
    var code;
    if (dropdown_property == 'PRIME') {
      // Prime is a special case as it is not a one-liner test.
      var functionName = coder.provideFunction_(
          'mathIsPrime',
          ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ + '(n) {',
          '  // https://en.wikipedia.org/wiki/Primality_test#Naive_methods',
          '  if (n == 2 || n == 3) {',
          '    return true;',
          '  }',
          '  // False if n is NaN, negative, is 1, or not whole.',
          '  // And false if n is divisible by 2 or 3.',
          '  if (isNaN(n) || n <= 1 || n % 1 != 0 || n % 2 == 0 ||' +
              ' n % 3 == 0) {',
          '    return false;',
          '  }',
          '  // Check all the numbers of form 6k +/- 1, up to sqrt(n).',
          '  for (var x = 6; x <= Math.sqrt(n) + 1; x += 6) {',
          '    if (n % (x - 1) == 0 || n % (x + 1) == 0) {',
          '      return false;',
          '    }',
          '  }',
          '  return true;',
          '}']);
      code = functionName + '(' + number_to_check + ')';
      return [code, coder.ORDER_FUNCTION_CALL];
    }
    switch (dropdown_property) {
      case 'EVEN':
        code = number_to_check + ' % 2 == 0';
        break;
      case 'ODD':
        code = number_to_check + ' % 2 == 1';
        break;
      case 'WHOLE':
        code = number_to_check + ' % 1 == 0';
        break;
      case 'POSITIVE':
        code = number_to_check + ' > 0';
        break;
      case 'NEGATIVE':
        code = number_to_check + ' < 0';
        break;
      case 'DIVISIBLE_BY':
        var divisor = coder.valueToCode(block, 'DIVISOR',
            coder.ORDER_MODULUS) || '0';
        code = number_to_check + ' % ' + divisor + ' == 0';
        break;
    }
    return [code, coder.ORDER_EQUALITY];
  };

  coder['math_change'] = function(block: any) {
    // Add to a variable in place.
    var argument0 = coder.valueToCode(block, 'DELTA',
        coder.ORDER_ADDITION) || '0';
    var varName = coder.variableDB_.getName(
        block.getFieldValue('VAR'), Blockly.Variables.NAME_TYPE);
    return varName + ' = (typeof ' + varName + ' == \'number\' ? ' + varName +
        ' : 0) + ' + argument0 + ';\n';
  };

  // Rounding functions have a single operand.
  coder['math_round'] = coder['math_single'];
  // Trigonometry functions have a single operand.
  coder['math_trig'] = coder['math_single'];

  coder['math_on_list'] = function(block: any) {
    // Math functions for lists.
    var func = block.getFieldValue('OP');
    var list, code;
    switch (func) {
      case 'SUM':
        list = coder.valueToCode(block, 'LIST',
            coder.ORDER_MEMBER) || '[]';
        code = list + '.reduce(function(x, y) {return x + y;})';
        break;
      case 'MIN':
        list = coder.valueToCode(block, 'LIST',
            coder.ORDER_COMMA) || '[]';
        code = 'Math.min.apply(null, ' + list + ')';
        break;
      case 'MAX':
        list = coder.valueToCode(block, 'LIST',
            coder.ORDER_COMMA) || '[]';
        code = 'Math.max.apply(null, ' + list + ')';
        break;
      case 'AVERAGE':
        // mathMean([null,null,1,3]) == 2.0.
        var functionName = coder.provideFunction_(
            'mathMean',
            ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ +
                '(myList) {',
              '  return myList.reduce(function(x, y) {return x + y;}) / ' +
                    'myList.length;',
              '}']);
        list = coder.valueToCode(block, 'LIST',
            coder.ORDER_NONE) || '[]';
        code = functionName + '(' + list + ')';
        break;
      case 'MEDIAN':
        // mathMedian([null,null,1,3]) == 2.0.
        var functionName = coder.provideFunction_(
            'mathMedian',
            ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ +
                '(myList) {',
              '  var localList = myList.filter(function (x) ' +
                '{return typeof x == \'number\';});',
              '  if (!localList.length) return null;',
              '  localList.sort(function(a, b) {return b - a;});',
              '  if (localList.length % 2 == 0) {',
              '    return (localList[localList.length / 2 - 1] + ' +
                'localList[localList.length / 2]) / 2;',
              '  } else {',
              '    return localList[(localList.length - 1) / 2];',
              '  }',
              '}']);
        list = coder.valueToCode(block, 'LIST',
            coder.ORDER_NONE) || '[]';
        code = functionName + '(' + list + ')';
        break;
      case 'MODE':
        // As a list of numbers can contain more than one mode,
        // the returned result is provided as an array.
        // Mode of [3, 'x', 'x', 1, 1, 2, '3'] -> ['x', 1].
        var functionName = coder.provideFunction_(
            'mathModes',
            ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ +
                '(values) {',
              '  var modes = [];',
              '  var counts = [];',
              '  var maxCount = 0;',
              '  for (var i = 0; i < values.length; i++) {',
              '    var value = values[i];',
              '    var found = false;',
              '    var thisCount;',
              '    for (var j = 0; j < counts.length; j++) {',
              '      if (counts[j][0] === value) {',
              '        thisCount = ++counts[j][1];',
              '        found = true;',
              '        break;',
              '      }',
              '    }',
              '    if (!found) {',
              '      counts.push([value, 1]);',
              '      thisCount = 1;',
              '    }',
              '    maxCount = Math.max(thisCount, maxCount);',
              '  }',
              '  for (var j = 0; j < counts.length; j++) {',
              '    if (counts[j][1] == maxCount) {',
              '        modes.push(counts[j][0]);',
              '    }',
              '  }',
              '  return modes;',
              '}']);
        list = coder.valueToCode(block, 'LIST',
            coder.ORDER_NONE) || '[]';
        code = functionName + '(' + list + ')';
        break;
      case 'STD_DEV':
        var functionName = coder.provideFunction_(
            'mathStandardDeviation',
            ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ +
                '(numbers) {',
              '  var n = numbers.length;',
              '  if (!n) return null;',
              '  var mean = numbers.reduce(function(x, y) {return x + y;}) / n;',
              '  var variance = 0;',
              '  for (var j = 0; j < n; j++) {',
              '    variance += Math.pow(numbers[j] - mean, 2);',
              '  }',
              '  variance = variance / n;',
              '  return Math.sqrt(variance);',
              '}']);
        list = coder.valueToCode(block, 'LIST',
            coder.ORDER_NONE) || '[]';
        code = functionName + '(' + list + ')';
        break;
      case 'RANDOM':
        var functionName = coder.provideFunction_(
            'mathRandomList',
            ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ +
                '(list) {',
              '  var x = Math.floor(Math.random() * list.length);',
              '  return list[x];',
              '}']);
        list = coder.valueToCode(block, 'LIST',
            coder.ORDER_NONE) || '[]';
        code = functionName + '(' + list + ')';
        break;
      default:
        throw Error('Unknown operator: ' + func);
    }
    return [code, coder.ORDER_FUNCTION_CALL];
  };

  coder['math_modulo'] = function(block: any) {
    // Remainder computation.
    var argument0 = coder.valueToCode(block, 'DIVIDEND',
        coder.ORDER_MODULUS) || '0';
    var argument1 = coder.valueToCode(block, 'DIVISOR',
        coder.ORDER_MODULUS) || '0';
    var code = argument0 + ' % ' + argument1;
    return [code, coder.ORDER_MODULUS];
  };

  coder['math_constrain'] = function(block: any) {
    // Constrain a number between two limits.
    var argument0 = coder.valueToCode(block, 'VALUE',
        coder.ORDER_COMMA) || '0';
    var argument1 = coder.valueToCode(block, 'LOW',
        coder.ORDER_COMMA) || '0';
    var argument2 = coder.valueToCode(block, 'HIGH',
        coder.ORDER_COMMA) || 'Infinity';
    var code = 'Math.min(Math.max(' + argument0 + ', ' + argument1 + '), ' +
        argument2 + ')';
    return [code, coder.ORDER_FUNCTION_CALL];
  };

  coder['math_random_int'] = function(block: any) {
    // Random integer between [X] and [Y].
    var argument0 = coder.valueToCode(block, 'FROM',
        coder.ORDER_COMMA) || '0';
    var argument1 = coder.valueToCode(block, 'TO',
        coder.ORDER_COMMA) || '0';
    var functionName = coder.provideFunction_(
        'mathRandomInt',
        ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ +
            '(a, b) {',
        '  if (a > b) {',
        '    // Swap a and b to ensure a is smaller.',
        '    var c = a;',
        '    a = b;',
        '    b = c;',
        '  }',
        '  return Math.floor(Math.random() * (b - a + 1) + a);',
        '}']);
    var code = functionName + '(' + argument0 + ', ' + argument1 + ')';
    return [code, coder.ORDER_FUNCTION_CALL];
  };

  coder['math_random_float'] = function(block: any) {
    // Random fraction between 0 and 1.
    return ['Math.random()', coder.ORDER_FUNCTION_CALL];
  };

  coder['math_atan2'] = function(block: any) {
    // Arctangent of point (X, Y) in degrees from -180 to 180.
    var argument0 = coder.valueToCode(block, 'X',
        coder.ORDER_COMMA) || '0';
    var argument1 = coder.valueToCode(block, 'Y',
        coder.ORDER_COMMA) || '0';
    return ['Math.atan2(' + argument1 + ', ' + argument0 + ') / Math.PI * 180',
        coder.ORDER_DIVISION];
  };

}


